xnu-792.2.4.tar.gz

[apple/xnu.git] / libkern / gen / OSAtomicOperations.c

diff --git a/libkern/gen/OSAtomicOperations.c b/libkern/gen/OSAtomicOperations.c
index c6e86aacacdbdb50376dbc9518a4a69c4e1ce991..4a1e7beb065eaca5426fa1d30033a27dd3c97b07 100644 (file)
--- a/libkern/gen/OSAtomicOperations.c
+++ b/libkern/gen/OSAtomicOperations.c
@@ -39,6 +39,11 @@ enum {
  *     which I wrote for NuKernel in a previous life with a different last name...)
  *
  * native Boolean      CompareAndSwap(UInt32 oldValue, UInt32 newValue, UInt32 * oldValuePtr);
+ *
+ * We've since implemented a few more of these -- OSAddAtomic, OSDequeueAtomic,
+ * OSEnqueueAtomic etc -- in assembler, either for speed or correctness.  See also the
+ * commpage atomic operations, and the platform specific versions.
+ * Like standards, there are a lot of atomic ops to choose from!
  */
 
 #ifndef __ppc__
@@ -66,6 +71,37 @@ SInt32       OSDecrementAtomic(SInt32 * value)
        return OSAddAtomic(-1, value);
 }
 
+void * OSDequeueAtomic(void ** inList, SInt32 inOffset)
+{
+       void *  oldListHead;
+       void *  newListHead;
+       
+       do {
+               oldListHead = *inList;
+               if (oldListHead == NULL) {
+                       break;
+               }
+               
+               newListHead = *(void **) (((char *) oldListHead) + inOffset);
+       } while (! OSCompareAndSwap((UInt32)oldListHead,
+                                       (UInt32)newListHead, (UInt32 *)inList));
+       
+       return oldListHead;
+}
+
+void   OSEnqueueAtomic(void ** inList, void * inNewLink, SInt32 inOffset)
+{
+       void *  oldListHead;
+       void *  newListHead = inNewLink;
+       void ** newLinkNextPtr = (void **) (((char *) inNewLink) + inOffset);
+       
+       do {
+               oldListHead = *inList;
+               *newLinkNextPtr = oldListHead;
+       } while (! OSCompareAndSwap((UInt32)oldListHead, (UInt32)newListHead,
+                                       (UInt32 *)inList));
+}
+
 #endif /* !__ppc__ */
 
 static UInt32  OSBitwiseAtomic(UInt32 and_mask, UInt32 or_mask, UInt32 xor_mask, UInt32 * value)
@@ -145,37 +181,6 @@ Boolean    OSTestAndClear(UInt32 bit, UInt8 * startAddress)
        return OSTestAndSetClear(bit, false, startAddress);
 }
 
-void * OSDequeueAtomic(void ** inList, SInt32 inOffset)
-{
-       void *  oldListHead;
-       void *  newListHead;
-       
-       do {
-               oldListHead = *inList;
-               if (oldListHead == NULL) {
-                       break;
-               }
-               
-               newListHead = *(void **) (((char *) oldListHead) + inOffset);
-       } while (! OSCompareAndSwap((UInt32)oldListHead,
-                                       (UInt32)newListHead, (UInt32 *)inList));
-       
-       return oldListHead;
-}
-
-void   OSEnqueueAtomic(void ** inList, void * inNewLink, SInt32 inOffset)
-{
-       void *  oldListHead;
-       void *  newListHead = inNewLink;
-       void ** newLinkNextPtr = (void **) (((char *) inNewLink) + inOffset);
-       
-       do {
-               oldListHead = *inList;
-               *newLinkNextPtr = oldListHead;
-       } while (! OSCompareAndSwap((UInt32)oldListHead, (UInt32)newListHead,
-                                       (UInt32 *)inList));
-}
-
 /*
  * silly unaligned versions
  */